#include "std.h"
#include "lpc_incl.h"
#include "stralloc.h"
#include "hash.h"
#include "comm.h"

/* used temporarily by SVALUE_STRLEN() */
int svalue_strlen_size;
#ifdef NOISY_DEBUG
void bp(void)
{
}
#endif
/*
 this code is not the same as the original code.  I cleaned it up to
 use structs to: 1) make it easier to check the driver for memory leaks
 (using MallocDebug on a NeXT) and 2) because it looks cleaner this way.
 --Truilkan@TMI 92/04/19

 modified to make calls to strlen() unnecessary and to remove superfluous
 calls to findblock().  -- Truilkan@TMI, 1992/08/05
 */

/*
 * stralloc.c - string management.
 *
 * All strings are stored in an extensible hash table, with reference counts.
 * free_string decreases the reference count; if it gets to zero, the string
 * will be deallocated.  add_string increases the ref count if it finds a
 * matching string, or allocates it if it cant.  There is no way to allocate
 * a string of a particular size to fill later (hash wont work!), so you'll
 * have to copy things from a static (or malloced and later freed) buffer -
 * that is, if you want to avoid space leaks...
 *
 * Current overhead:
 *	sizeof(block_t) per string (string pointer, next pointer, and a short
 *  for refs). Strings are nearly all fairly short, so this is a significant
 *  overhead - there is also the 4 byte malloc overhead and the fact that
 *  malloc generally allocates blocks which are a power of 2 (should write my
 *	own best-fit malloc specialised to strings); then again, GNU malloc
 *	is bug free...
 */

/*
 * there is also generic hash table management code, but strings can be shared
 * (that was the point of this code), will be unique in the table,
 * require a reference count, and are malloced, copied and freed at
 * will by the string manager.  Besides, I wrote this code first :-).
 * Look at htable.c for the other code.  It uses the Hash() function
 * defined here, and requires hashed objects to have a pointer to the
 * next element in the chain (which you specify when you call the functions).
 */

#ifdef STRING_STATS
int num_distinct_strings = 0;
int bytes_distinct_strings = 0;
int overhead_bytes = 0;
int allocd_strings = 0;
int allocd_bytes = 0;
int search_len = 0;
int num_str_searches = 0;
#endif

#define StrHash(s) (whashstr((s), 20) & (htable_size_minus_one))

#define hfindblock(s, h) sfindblock(s, h = StrHash(s))
#define findblock(s) sfindblock(s, StrHash(s))

INLINE_STATIC block_t *sfindblock(char *, int);

/*
 * hash table - list of pointers to heads of string chains.
 * Each string in chain has a pointer to the next string and a
 * reference count (char *, int) stored just before the start of the string.
 * HTABLE_SIZE is in config.h, and should be a prime, probably between
 * 1000 and 5000.
 */

static block_t **base_table = (block_t **) 0;
static int htable_size;
static int htable_size_minus_one;
INLINE_STATIC block_t *alloc_new_string(char *, int);

void init_strings()
{
	int x, y;

	/* ensure that htable size is a power of 2 */
	y = HTABLE_SIZE;
	for (htable_size = 1; htable_size < y; htable_size *= 2)
		;
	htable_size_minus_one = htable_size - 1;
	base_table = CALLOCATE(htable_size, block_t *,
			TAG_STR_TBL, "init_strings");
#ifdef STRING_STATS
	overhead_bytes += (sizeof(block_t *) * htable_size);
#endif

	for (x = 0; x < htable_size; x++)
	{
		base_table[x] = 0;
	}
}

/*
 * Looks for a string in the table.  If it finds it, returns a pointer to
 * the start of the string part, and moves the entry for the string to
 * the head of the pointer chain.  One thing (blech!) - puts the previous
 * pointer on the hash chain into fs_prev.
 */

INLINE_STATIC block_t *
sfindblock(char * s, int h)
{
	block_t *curr, *prev;

	curr = base_table[h];
	prev = NULL;
#ifdef STRING_STATS
	num_str_searches++;
#endif

	while (curr)
	{
#ifdef STRING_STATS
		search_len++;
#endif
		if (*(STRING(curr)) == *s && !strcmp(STRING(curr), s))
		{ /* found it */
			if (prev)
			{ /* not at head of list */
				NEXT(prev) = NEXT(curr);
				NEXT(curr) = base_table[h];
				base_table[h] = curr;
			}
			return (curr); /* pointer to string */
		}
		prev = curr;
		curr = NEXT(curr);
	}
	return ((block_t *) 0); /* not found */
}

char *
findstring(char * s)
{
	block_t *b;

	if ((b = findblock(s)))
	{
		return STRING(b);
	}
	else
	{
		return (NULL);
	}
}

/* alloc_new_string: Make a space for a string.  */

INLINE_STATIC block_t *
alloc_new_string(char * string, int h)
{
	block_t *b;
	int len = strlen(string);
	int size;

	if (len > max_string_length)
	{
		len = max_string_length;
	}
	size = sizeof(block_t) + len + 1;
	b = (block_t *) DXALLOC(size, TAG_SHARED_STRING, "alloc_new_string");
	strncpy(STRING(b), string, len);
	STRING(b)[len] = '\0'; /* strncpy doesn't put on \0 if 'from' too
	 * long */
	SIZE(b) = (len > USHRT_MAX ? USHRT_MAX : len);
	REFS(b) = 1;
	NEXT(b) = base_table[h];
	base_table[h] = b;
	ADD_NEW_STRING(SIZE(b), sizeof(block_t));ADD_STRING(SIZE(b));
	return (b);
}

char *
make_shared_string(char * str)
{
	block_t *b;
	int h;

	b = hfindblock(str, h); /* hfindblock macro sets h = StrHash(s) */
	if (!b)
	{
		b = alloc_new_string(str, h);
	}
	else
	{
		if (REFS(b))
			REFS(b)++;
		ADD_STRING(SIZE(b));
	}NDBG(b);
	return (STRING(b));
}

/*
 ref_string: Fatal to call this function on a string that isn't shared.
 */

char *
ref_string(char * str)
{
	block_t *b;

	b = BLOCK(str);
#ifdef DEBUG
	if (b != findblock(str))
	{
		fatal("stralloc.c: called ref_string on non-shared string: %s.\n", str);
	}
#endif				/* defined(DEBUG) */
	if (REFS(b))
		REFS(b)++;
	NDBG(b);ADD_STRING(SIZE(b));
	return str;
}

/* free_string: fatal to call free_string on a non-shared string */
/*
 * free_string - reduce the ref count on a string.  Various sanity
 * checks applied.
 */

void free_string(char * str)
{
	block_t **prev, *b;
	int h;

	b = BLOCK(str);
	DEBUG_CHECK1(b != findblock(str),"stralloc.c: free_string called on non-shared string: %s.\n", str);

	/*
	 * if a string has been ref'd USHRT_MAX times then we assume that its used
	 * often enough to justify never freeing it.
	 */
	if (!REFS(b))
		return;

	REFS(b)--;
	SUB_STRING(SIZE(b));

	NDBG(b);
	if (REFS(b) > 0)
		return;

	h = StrHash(str);
	prev = base_table + h;
	while ((b = *prev))
	{
		if (STRING(b) == str)
		{
			*prev = NEXT(b);
			break;
		}
		prev = &(NEXT(b));
	}

	DEBUG_CHECK1(!b, "free_string: not found in string table! (\"%s\")\n", str);

	SUB_NEW_STRING(SIZE(b), sizeof(block_t));
	FREE(b);
	CHECK_STRING_STATS;
}

void deallocate_string(char * str)
{
	int h;
	block_t *b, **prev;

	h = StrHash(str);
	prev = base_table + h;
	while ((b = *prev))
	{
		if (STRING(b) == str)
		{
			*prev = NEXT(b);
			break;
		}
		prev = &(NEXT(b));
	}DEBUG_CHECK1(!b,"stralloc.c: deallocate_string called on non-shared string: %s.\n", str);

	FREE(b);
}

int add_string_status(outbuffer_t * out, int verbose)
{
#ifdef STRING_STATS
	if (verbose == 1)
	{
		outbuf_add(out, "All strings:\n");
		outbuf_add(out, "-------------------------\t Strings    Bytes\n");
	}
	if (verbose != -1)
	outbuf_addv(out, "All strings:\t\t\t%8d %8d + %d overhead\n",
			num_distinct_strings, bytes_distinct_strings, overhead_bytes);
	if (verbose == 1)
	{
		outbuf_addv(out, "Total asked for\t\t\t%8d %8d\n",
				allocd_strings, allocd_bytes);
		outbuf_addv(out, "Space actually required/total string bytes %d%%\n",
				(bytes_distinct_strings + overhead_bytes) * 100 / allocd_bytes);
		outbuf_addv(out, "Searches: %d    Average search length: %6.3f\n",
				num_str_searches, (double) search_len / num_str_searches);
	}
	return (bytes_distinct_strings + overhead_bytes);
#else
	if (verbose)
		outbuf_add(out,
		        "<String statistics disabled, no information available>\n");
	return 0;
#endif
}

#ifdef DEBUGMALLOC_EXTENSIONS
#define DME 0,
#else
#define DME
#endif

/* This stuff needs a bit more work, otherwise FREE_MSTR() will crash on this
 malloc_block_t the_null_string_blocks[2] = { { DME 0, 1 }, { DME 0, 0 } };

 char *the_null_string = (char *)&the_null_string_blocks[1];
 */

#ifdef DEBUGMALLOC
char *int_new_string(int size, char * tag)
#else
char *int_new_string(int size)
#endif
{
	malloc_block_t *mbt;

#if 0
	if (!size)
	{
		the_null_string_blocks[0].ref++;
		ADD_NEW_STRING(0, sizeof(malloc_block_t));
		return the_null_string;
	}
#endif

	mbt =
	        (malloc_block_t *) DXALLOC(size + sizeof(malloc_block_t) + 1, TAG_MALLOC_STRING, tag);
	if (size < USHRT_MAX)
	{
		mbt->size = size;
		ADD_NEW_STRING(size, sizeof(malloc_block_t));
	}
	else
	{
		mbt->size = USHRT_MAX;
		ADD_NEW_STRING(USHRT_MAX, sizeof(malloc_block_t));
	}
	mbt->ref = 1;
	ADD_STRING(mbt->size);CHECK_STRING_STATS;
	return (char *) (mbt + 1);
}

char *extend_string(char * str, int len)
{
	malloc_block_t *mbt;
#ifdef STRING_STATS
	int oldsize = MSTR_SIZE(str);
#endif

	mbt =
	        (malloc_block_t *) DREALLOC(MSTR_BLOCK(str), len + sizeof(malloc_block_t) + 1, TAG_MALLOC_STRING, "extend_string");
	if (len < USHRT_MAX)
	{
		mbt->size = len;
	}
	else
	{
		mbt->size = USHRT_MAX;
	}ADD_STRING_SIZE(mbt->size - oldsize);CHECK_STRING_STATS;

	return (char *) (mbt + 1);
}

#ifdef DEBUGMALLOC
char *int_alloc_cstring(char * str, char * tag)
#else
char *int_alloc_cstring(char * str)
#endif
{
	char *ret;

	ret = (char *) DXALLOC(strlen(str) + 1, TAG_STRING, tag);
	strcpy(ret, str);
	return ret;
}
